"Media studies" by Marshall McLuhan, Quentin Fiore, 1967
In The Medium is the Massage: An Inventory of Effects, Penguin Publisher pp 68-69
An important historical book, which had a significant impact on the debates around media in the late 1960s. Even though more recently scholars have claimed it suffers from "technological determinism", this book remains a fascinating piece of theoretical writing presented in a compelling graphical format (which is why Fiore, the designer, gets credited as co-author!). Here is a small sample, but the book is worth reading in its gloriously pop-layout entirety!
Difficulty : 
Time : < 5 minutes
FileSize : 1.6 MB
Filed under : Theory